1. Field of the Invention
This application relates generally to magnetic write heads for magnetic recording, and more specifically to apparatuses and methods for controlling the flying-height distance between the write head and the magnetic medium.
2. Description of the Related Art
The areal density of magnetic recording depends in part on the flying-height distance between the magnetic medium and the air-bearing surface (“ABS”) of the magnetic write head. As areal densities continue to increase, the flying-height distance continues to decrease. In addition, the flying-height distances among different write heads .have variations (e.g., due to variations in the manufacturing process). The ranges of these variations have remained substantially the same as flying-height distances have decreased, such that these variations correspond to larger percentages of the flying-height distance.
In addition, the flying-height distance of a particular write head can vary during operation. For example, a standard magnetic write head heats up to different temperatures as the write head is driven at different frequencies. This heat can cause at least a portion of the write head to expand (via the coefficient of thermal expansion) such that at least a portion of the write head protrudes towards the magnetic medium, thereby reducing the flying-height distance. Occasionally, the write head can contact the magnetic medium due to this thermally-reduced flying-height distance. The resulting impact can cause the write head to drift off-track, thereby causing a delay in the time for data access. While such impacts can be avoided by increasing the flying-height distance, larger flying-height distances negatively affect the performance of the write head and reduce the areal density that can be achieved.